A wireless communication terminal applied to, for example, CDMA (Code Division Multiple Access) communication starts a channel acquisition operation when sending or receiving a signal or when transferring data. Further, the terminal obtains configuration information and timing information of the acquired channel, and obtains position registration information etc. synchronized with the timing of the acquired channel.
The received field strength of this channel sometimes remarkably falls according to a usage environment of the wireless communication terminal (topography, buildings, etc.) When the received field strength of the channel is low, regardless of that the fact that the signal of the channel was received, it is judged that the channel could not be acquired and “in-area” reset processing is shifted to.
In this “in-area” reset processing, the wireless communication terminal runs a system scan where it acquires a channel by a predetermined cycle.
In this regard, when the wireless communication terminal is out of the area, the wireless communication terminal internally turns a flag showing it is “out of area” (out-of-area flag) ON. In such a situation, even if the user performs a send operation, the terminal will not start up the send processing since the possibility of transmission is low while the out-of-area flag is ON and in general for saving power.
Further, once a terminal is judged “out of area”, the “in-area” reset processing is carried out by a predetermined cycle, but the communication schemes for running a system scan for reset are limited and the time required for “in-area” reset can no longer be ignored.
For example, when exiting from or entering to a tunnel or at another where the usage environment is extremely different, desirably the “in-area” reset processing is carried out immediately after exiting from the tunnel. However, immediate reset is not possible unless at the timing of an “in-area” reset acquisition operation. Further, even if performing the “in-area” reset acquisition processing, this does not always lead to an immediate “in-area” reset.
In order to overcome the problem described above, the art is known of performing a channel acquisition operation if performing a send operation even when the terminal is judged “out of area” (see, for example, Patent Document 1).
Patent Document 1: Japanese Patent Publication (A) No. 2003-23665